Around 45% of all primary brain tumors are gliomas. The survival rate from having gliomas is varied. Factors contributing to this range of success of treating gliomas include the types (grade) of gliomas and stage of the glioma. In addition, the position of the tumor in the brain and the symptoms caused by the tumor are also very important factors. For example, brain stem gliomas are particularly difficult to treat, whatever their grade. The brain stem is a very complicated and delicate part of the brain and completely removing the tumor is often near impossible. Furthermore, high doses of radiotherapy are not recommended either because this may cause too much damage to the normal brain stem. Sometimes, conventional chemotherapy is often the last remaining therapies for such inoperable tumor.